It is basically a bread boarded Arduino UNO. The sketch runs four tests. The first loop loads all zeros in the memory and then will read them back. The second loop loads all ones. Loop three and four load alternate 1ís and 0ís.
There are three LEDís. The green LED will light until an error occurs. The red LED is dual function. If all four loops pass it will blink several times and then the four loops will repeat. If any of the loops fails only the RED LED will remain lit. The blue LED will light and stay lit if the first set of 4 tests passed.
This is an updated design of my DRAM tester. This uses a 1284P avr chip. The Atmel studio
project and schematic are included in this zip file. Running without the Arduino
platform the timing is within sepcs of the dram.